Classification system



March 21 1939. w FOULKE 2,150,918

CLASSIFICATION SYSTEM Filed Jan. 21, 1937 3 Sheets-Sheet l March 21, 1939. w. B. FOULKE CLASSIFICATION SYSTEM 5 Shets-Sheet 2 Filed Jan. 21, 1957 INVENTOR .fouike March 21, 1939.

W. B. FOULKE CLASSIFICATION SYSTEM Filed Jan. 21, 1937 3 Sheets-Sheet 3 I ma: ll.

NEY

Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE du Pont de Nemours a Company, Wilmingt Del., a corporation of Delaware Application January 21, 1937, Serial No. 121,386

9 Claims.

a. This invention relates to the separation of solids of different specific graviifies by the use of a liquid of intermediate specific gravity. The

invention has particular application to the separation of coal from its indigenous impurities and it will be described in that connection, but that particular descrlption is illustrative, not limiting. B. In copending application, Alexander et al., filed August 31, 1936, Serial No. 98,818, there is described a new process and a new apparatus for carrying out the separation of materials of different specific gravities. In that invention coal is wetted with an aqueous solution containing a proportion of an active agent, an example of which is tannic acid, and is immersed in a separating fluid of specific gravity intermediate the specific gravities of the coal and the impurities. The classified materials are removed separately from the apparatus and the washing fluid is treated in a particular, inventive manner for the recovery of the parting liquid. C. Itis an object of this invention to separate coal from slate and other minerals from impurities by an improved. process. Another object of the .invention is to carry out the improved process or the process described in said earlier filed application by an improved apparatus. Other objects of the invention will be in part elsewhere herein described and in part apparent;

D. The objects of the invention are accomplished, generally speaking, by subjecting the materials to be separated to the action of a moving stream of light liquid, such as water, and thereafter subjecting the so-classifled materials to the action of a liquid body having specific gravity intermediate the specific gravities of the materials to be separated. The objects of the invention are also accomplishedto a degree by the details of the apparatus and method more fully hereinafter described.

E. In the drawings Figure 1 IS a plan view oil the apparatus; Figure 2 is a section on the line 2--2 of Figure 1; Figure 3 is a section on the line 3--3 of Figure 1; Figure 4 is a section on the line 4-4 of Figure 2; Figure 5 is a section on the line 5--5 of Figure 2; Figure 6 is a section on the line 6-6 of Figure 2, and Figure '1 is 'a detail of the means of sealing removable covers of the apparatus.

F. In the drawings, I0 is an enclosed tank; II is a sump; I2 is an inclined portion in the bottom of the tank leading upwardly and forwardly from the bottom of the sump; I3 is a weir; I4 is a compartment formed by the bottom of the tank I0, weir I3, and wall I5; I6 is an inclined bottom of the tank beyond the wall I5; I1 is an end pipe forming a tank wall. By this construction there is provided what are in effect two tanks, the first of which, having inclined bottom I2, will be called the first tank, and the second (on. zoa-rm of which, having an inclined bottom I6, will be called the second tank. I8 is a slot in the wall I1 which permits the exit of the screen; I9 is a tank-like extension of the chamber I9; I9I is an end wall of tank III which extends downward into the tank I9 to a position below that normally occupied by the liquid of tank I9; IBI is an outer wall of the tank enclosing the recovery apparatus and screen.

G. Referring to the liquid handling portion of the apparatus, is a pipe leading from a supply of the parting liquid which is to be used to eifect the classification; 2i is a valve; 22 is a valve in pipe 23; 24 is a pipe connecting pipes 20 and 23 with sumpII; 25 is a pump in pipe 23; 26 is a pipe connecting chamber I4 with settling tank 21; 28 is a pipe connecting the lowest point of tank it with sump II; 29 is a pipe extending from the liquid level in tank I8 to tank 21; I92 is a pipe and I93 is a valve therein whereby to flll and drain tank I9. Settling tank 21 has an inclined bottom 219; 2II-212 are perforated baffle plates forminga chamber within which the pipes 26 and 29 may discharge; 213 are inclined perforated baffle plates in the settling tank; 214 is an imperi'orate baille extending below the liquid level of the tank; 215 is a weir across the end of the tank; 213 is a pipe leading from the chamber beyond the weir; 211 is a pump in the pipe 216; 218 is a pipe; 219 is a valve therein; 280 is a pipe connecting pipes 218 and 215 with sprays28I 282 are flexible baflles between adjacent sprays; 283 is a second pipe leading from pipes 215 and 218; 284 are sprays placed beneath the screen for operation thereagainst; 285 is a pipe opening at 286 into the tank I6 and at 281 into the tank I2; opening 281 is at least in part above the level at which the parting liquid is maintained in the tank I2.

H. Referring now to the mineral-handling equipment, 30 is a chute; 3| is an opening from the chute through the side of the tank I2; 32 is a baille extending from above the opening 3| to proximity to the bottom I2; 320 is a flap, preferably flexible, attached to the lower end of battle 32; 33 are a series of rollers; 35 is a wire screen, which may be of Fourdrinler, wedge wire, or any other satisfactory type, trained around the rollers 33. The wire passes about one roller 33, through an opening 330 in the tank III, in back of the ballle 32, around roller 33, and beneath the bafile whose flap 320 makes contact with the upper surface thereof and prevents solids from piling up against the roller 33, passes over the series of small rollers 33 and over the chamber I4 and wall I5 and about tank I6, around end rollers 33 through slot I8 in wall I1, and back beneath the tanks over adjustable roller 33a. Other rollers may also be made adjustable in known ways if it is desired. One such way is in proximity to opening 330. 36 is an angle-shaped partition dividing the screen and closely conforming to the surface thereof; 35 is a screen baflle extending from the forward end of the opening 3| to the partition 36, the bottom edge of the said screen being beneath the surface of the parting liquid but not so close to the screen that materials would be prevented from passing beneath it. 3131 are side guards to prevent materials from jamming between the screen and the sides of the tank and to prevent wear on the tank sides. 40 is a scraper type discharge conveyor operating in the water-sealed tank I9; 4i is a partition in the tank I9 which in effect divides the conveyor into two parts; is a framework within the tank; 5l-5I are shafts mounted in the framework bearing rollers 52'52; 53 are belts trained over the rollers; 54 are rakes carried by the belts; and 55 is a motor and connections for driving the shafts, the wheels, the belts, and

the rakes.

I. The operation of the device will be described by following through the apparatus the various materials and the functions which they perform or which are performed upon them. Assuming that the material to be classified is run-of-themine anthracite coal, which contains of course a certain amount of admixed slate, dirt, and other impurities, the tank l2 will be filled with heavy liquid having a specific gravity between that of the coal and that of the main impurity to the heavy liquid level through pipe 20. Thereafter water will be run in on top of the heavy liquid until a blanket is formed. The run-of-the-mine coal will be admitted through the opening 30 and opening Ii, the sprays 28l will be started, and the tank I will be filled until water runs through the opening 286 down the pipe 285 and through the opening 281 which is beneathpoint 3| of admittance for the coal. As the water enters through opening 281, it has considerable velocity and moves in a stream across the surface of the heavy liquid carrying with it to the other side of the apparatus all materials which float on the heavy liquid and serving to give a preliminary hydraulic classification to the solids before they are acted upon by the heavy liquid. The entire apparatus being started, the material heavier than the liquid, which will hereinafter be called sinks, falls from the opening ll through the water issuing from opening 281 and toward the bottom of the tank l2. Some of it encounters the ballle I2 and all of it eventually encounters the moving screen 34 and a point in proximity to the point of admittance. The sinks are picked up by the screen, carried beneath the baille screen 3!, and over the wall ii to the showers Ill. The partition ll confines the sinks to and on the side of the apparatus. The material which fioats upon the surface of the heavy liquid is carried by the stream of water over and past the partitions 34 and "I to the other side of the machine. The rakes catch the material and drive it forward until it makes contact with the moving screen which picks it up and takes it to the showers.

J. The sprays from the showers impinge both from above and beneath and thoroughly wash the material, freeing it from parting liquid transported on its surface. The wash water and the mixed heavy liquid are caught in the tank It; the heavy liquid settles out at the low point of the tank and is carried through pipe 28 to sump II. The pipe may be left open constantly or may be opened from time to time by means of a valve if it is desirable. Having passed beneath the showers, the coal is discharged over the roller 23 into the water-sealed tank 19 where it is picked up by the scraper conveyor 40, which is divided by the partition 4| into two parts, one for sinks and one for floats.

K. The heavy liquid in the tank I2 is maintained at its level by that returned through pipe 28 and by the admission of other heavy liquid through pipe 24. The level of the water in the system is maintained by weir I 3 in conjunction with' water admitted through pipe 285. The water, reaching the level of the weir l3, flows into the chamber l4 and through pipe 26 to settling tank 21. Baflles 212 and 211 form a turbulence chamber within the tank 21, within which the turbulence caused by the entry of the liquid is absorbed, the liquid in the remainder of the tank flowing quietly. The perforated baflles 21l, 212, and 213 act upon the flowing liquids to separate the heavy from the light liquid. The heavy liquid sinks to the bottom of the tank which is provided with an inclined bottom 210 and is withdrawn from the lowest end thereof through pipe 24 and is returned through pipe 23 to the sump I l. The screen passes out of the water before it passes the wall i5 and a first washing takes place in the water of tank i2, a first draining takes place above chamber l4 and, consequently, a large portion of heavy liquid is caught in chamber l4 and tank l2. Passing the wall i5 between the two tanks, the screen carries the material beneath and above a series of showers which free it from the remaining heavy liquid. The wash water from tank It passes through opening 286 or, if that opening is incapable of absorbing the entire quantity, through pipe 29 whose opening is at the level of opening 286 to the turbulence chamber of tank 21. The liquids, bled substantially free from heavy liquid by the bailles 213,

passes beneath the imperforate bail'ie 214 which from whence it is withdrawn through pipe 21 and used again in the showers.

L. The side guards I1 and the partition I8 are worn in to the surface of the screen by permitting light contact during the first operation of the screen. Thereafter the fit is so close that it is only exceptionally that solid materials get between it and the screen. In order to take care of such solid materials, these partitions are made so that they are self-freeing. This is accomplished by making the partitions narrower toward the discharge end of the machine. In that way a particle caughtbetween the screen and the board is carried in the direction of the screen and constantly approaches a narrower part of the board until it is finally discharged from beneath M. By this inventionthere is produced an efficient apparatus and process for the classification of solids. The unit is efilcient, self-contained. and subject to wide variation in detail without departing from the scope of the invention.

rated tanks, means to admit aliquid to one said tank, means to maintain the liquid level comprising a weir and compartment, means to flow a second liquid upon the first, means forremoving solids. comprising a movable screen operating in proximity to the bottom of the first and above the second tank, means in part submerged for partitioningthe screen, means at one side of the partition to admit solids to the flowing liquid, the flow of the liquid being so directed that the floats will be carried beyond the partition before encountering the screen, means above the second tank to wash the separated solids, means connecting the second tank with the first to provide the flow of )iquid, a settling tank having an inclined bottom and bleeder baffles, means connecting the weired compartment and the drainage tank with the settling tank, means for returning liquid to the first tank from the depth of the settling tank, means for supplying liquid from the top of the settling tank to said washing means, and means for adjusting and driving the screen.

2. In a process for the classification of solids an hermetically sealed chamber containing separated tanks, means to admit a liquid to one said tank, means to maintain the liquid level comprising a weir and compartment, means to flow a second liquid upon the first, means for removing solids comprising a movable screen operating in proximity to the bottom of the first and above the second tank, means in part submerged for partitioning the screen, means at one side of the partition to admit solids to the flowing liq?- uid, the flow of the liquid being so directed that the floats will be carried beyond the partition before encountering the screen, means above the second tank to wash the separated solids, means connecting the second tank with the first to provide the fiow of liquid, a settling tank having an inclined bottom and bleeder baiiies, means connecting the weired compartment and the drainage tank with the settling tank, means for returning liquid to the first tank from the depth of the settling tank, and means for supplying liquid from the top of the settling tank to said washing means.

3. In a process for the classification of solids an hermetically sealed chamber containing separated tanks, means to admit a liquid to one said tank, means to maintain the liquid level comprising a weir and a compartment, means to flow a second liquid upon the first, means for removing solids comprising a movable screen operating in proximity to the bottom of the first and above the second tank, means in part submerged for partitioning the screen, means at one side of the partition to admit solids to the flowing liquid, the flow of the liquid being so directed that the floats will be carried beyond the partition before encountering the screen, means above the second tank to wash the separated solids, means connecting the second tank with the first to provide the flow of liquid, a setling tank having means for separating liquids of different densities, means connecting the weired compartment and the drainage tank with the settling tank, means for returning heavy liquid to the first tank, and means for supplying light liquid to the said washing means.

4. In a process for the classification of solids an hermetically sealed chamber containing separated tanks, means to admit a liquid to one said tank, means to flow a second liquid upon the first, a weir in said tank means for removing solids comprising a movable screen operating in proximity to the bottom of one and above another said tanks, means for partitioning the screen, means at one side of the partition to admit solids to the flowing liquid, the flow of the liquid being so diturning heavy liquid to the first tank, and means for supplying light liquid to the said washing means.

5. In a process for the classification of solids an hermetically sealed chamber containing separated tanks, means to admit a liquid to one said tank, means to flow a second liquid upon the first, means for removing solids comprising a movable screen operating in proximity to the bottom of the first and above the second tank, means partitioning the screen, means at one side of the partition to admit solids to the flowing liquid, the flow of the liquid being so directed that the floats willbe carried beyond the partition before encountering the screen, above the second tank to wash the separated solids, a settling tank having means for separating liquids of different densities, means to direct the wash liquid thereto and means for recovering heavy liquid.

6. An apparatus comprising a plurality of tanlm. means to admit a parting liquid to one said tank, means to admit solids to said tank for classification, means for removing the classified solids from said first tank to a position above another of said tanks comprising a screen, means comprising a transversely directed stream of water for directing the classified solids to different portions of the screen, means for washing the classified solids on the screen, means for separating parting liquid from the wash liquids in the second tank, means for returning the parting liquid to the first tank, and means for reusing the wash liquid.

'7. Anapparatus comprising a tank, means to admit a parting liquid to said tank, means at the side of the tank to admit solids to said tank for classification, means for removing the classified solids from said tank to another tank comprising a screen, and means for directing the floating solids to remoteportions of the screen comprisinB a stream of liquid flowing transversely of the tank.

' 8. The process which comprises plunging a mass containing particles of diflerent densities into a stream of water having sufllcient depth and velocity to produce an initial horizontal classificastream to the vertical classifying eflect of a body of a liquid having a density between the densities of the said particles.

means 

